From 9a22f920a366db96034c3230ca513bc5a4be38d2 Mon Sep 17 00:00:00 2001
From: Amy Retzerau <amy.retzerau@gmail.com>
Date: Sun, 24 Aug 2025 13:23:46 +0200
Subject: [PATCH] feat: rendered first polygon

---
 main.cpp | 98 +++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 86 insertions(+), 12 deletions(-)

diff --git a/main.cpp b/main.cpp
index f0f299b..fbd66a5 100644
--- a/main.cpp
+++ b/main.cpp
@@ -2,18 +2,26 @@
 #include <GLFW/glfw3.h>
 #include <cstdio>
 
-void display() {
-    glClear(GL_COLOR_BUFFER_BIT);
-    glBegin(GL_TRIANGLES);
-    glColor3f(1.0, 0.0, 0.0);
-    glVertex2f(-0.5, -0.5);
-    glColor3f(0.0, 1.0, 0.0);
-    glVertex2f(0.5, -0.5);
-    glColor3f(0.0, 0.0, 1.0);
-    glVertex2f(0.0, 0.5);
-    glEnd();
-    glFlush();
-}
+float vertices[] = {
+    -0.5f, -0.5f, 0.0f,
+     0.5f, -0.5f, 0.0f,
+     0.0f,  0.5f, 0.0f
+}; 
+
+
+const char *vertexShaderSource = "#version 330 core\n"
+    "layout (location = 0) in vec3 aPos;\n"
+    "void main()\n"
+    "{\n"
+    "   gl_Position = vec4(aPos.x, aPos.y, aPos.z, 1.0);\n"
+    "}\0";
+
+const char *fragmentShaderSource = "#version 330 core\n"
+    "out vec4 FragColor;\n"
+    "void main()\n"
+    "{\n"
+    "   FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);\n"
+    "}\n\0";
 
 /*void framebuffer_size_callback(GLFWwindow* window, int width, int height)
 {
@@ -26,6 +34,65 @@ void processInput(GLFWwindow *window)
         glfwSetWindowShouldClose(window, true);
 }
 
+unsigned int initVBO() {
+    unsigned int VBO;
+    glGenBuffers(1, &VBO);
+    glBindBuffer(GL_ARRAY_BUFFER, VBO);
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    return VBO;
+}
+
+unsigned int initVAO() {
+    unsigned int VAO;
+    glGenVertexArrays(1, &VAO);
+    glBindVertexArray(VAO);
+    // 2. copy our vertices array in a buffer for OpenGL to use
+    glBindBuffer(GL_ARRAY_BUFFER, initVBO());
+    glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    // 3. then set our vertex attributes pointers
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+    glEnableVertexAttribArray(0);
+    return VAO;
+}
+
+
+unsigned int compVertexShader() {
+    unsigned int vertexShader;
+    vertexShader = glCreateShader(GL_VERTEX_SHADER);
+    glShaderSource(vertexShader, 1, &vertexShaderSource, NULL);
+    glCompileShader(vertexShader);
+    return vertexShader;
+}
+
+unsigned int compFragmentShader() {
+    unsigned int fragmentShader;
+    fragmentShader = glCreateShader(GL_FRAGMENT_SHADER);
+    glShaderSource(fragmentShader, 1, &fragmentShaderSource, NULL);
+    glCompileShader(fragmentShader);
+    return fragmentShader;
+}
+
+unsigned int compShader() {
+    unsigned int shaderProgram;
+    shaderProgram = glCreateProgram();
+    unsigned int vert = compVertexShader();
+    unsigned int frag = compFragmentShader();
+    glAttachShader(shaderProgram, vert);
+    glAttachShader(shaderProgram, frag);
+    glLinkProgram(shaderProgram);
+    
+    glDeleteShader(vert);
+    glDeleteShader(frag);  
+
+    return shaderProgram;
+}
+
+void linkVBO() { 
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+    glEnableVertexAttribArray(0); 
+}
+
+
 int main(int argc, char** argv) {
 
     GLFWwindow* window;
@@ -52,6 +119,9 @@ int main(int argc, char** argv) {
 
     glViewport(0, 0, 800, 600);
 
+    unsigned int shaderProgramm = compShader();
+    unsigned int VAO = initVAO();
+
     while (!glfwWindowShouldClose(window))
     {
         processInput(window);
@@ -61,7 +131,11 @@ int main(int argc, char** argv) {
         glClearColor(0.2f, 0.3f, 0.3f, 1.0f);
         glClear(GL_COLOR_BUFFER_BIT);
 
+	
+	glUseProgram(shaderProgramm);
 
+        glBindVertexArray(VAO);
+	glDrawArrays(GL_TRIANGLES, 0, 3);
         /* Poll for and process events */
         glfwPollEvents();